Scientists confirm existence of water history on Mars

This rock outcrop found by NASA's Curiosity rover shows evidence for an ancient, flowing stream on Mars (Courtesy NASA/JPL-Caltech/MSSS)

Saturday, June 1, 2013, 10:28 AM - It's been talked about a lot but now scientists have definitive proof that many of the surface features found on Mars were indeed cut by flowing water.

Curiosity provides a stereo view of a rock that bears rounded pebbles, similar to Earth (Courtesy NASA/JPL-Caltech/MSSS)

Scientists now have conclusive evidence that flowing water once existed on Mars.

The findings come from NASA's Curiosity rover and show that valleys, channels and deltas viewed from orbit were indeed cut by water.

The rover looked at rounded pebbles found in the large Gale Crater.

Researchers noticed that the stones' smooth appearance was exactly the same as gravels found on Earth.

When pebbles are thrown by moving water, they eventually loose their pointed edges as they get slammed into the riverbed.

Once at rest, they will often appear in a overlapping formation.

This pattern has been found at numerous locations along the 150 kilometre-wide crater.

The rocks are part of an ancient streambed and are the first ever found on Mars that contain river-base gravels.

"These conglomerates look amazingly like streambed deposits on Earth," said Rebecca Williams of the Planetary Science Institute, Tucson, Ariz., in a report. "Most people are familiar with rounded river pebbles. Maybe you've picked up a smoothed, round rock to skip across the water. Seeing something so familiar on another world is exciting and also gratifying."

NASA believes that ancient streams could have carried these rocks a few kilometres.

The pebbles were first discovered and photographed in September, just 7 weeks after Curiosity landed in Gale.

After analyzing the pictures in more detail, scientists noticed many similarities to Earth.

Another feature that stood out was alternating layers of pebbles and sand. This is a common element in streambed deposits on Earth.

Mars' polar ice caps hold large quantities of water. There is also evidence to show different environments with liquid water did exist.

The only problem is none of the samples could provide stream flow information like the pebbles.